During the manufacturing of an aircraft, components with variable tolerance restrictions are assembled, thereby resulting in tolerance buildups. This buildup may create problems when installing components. To avoid these problems, connecting methods with a degree of adjustability are desired. More specifically, a connecting bracket that may be adjusted in 2 or 3 of the aircraft's coordinate directions (forward/aft, inboard/outboard, and up/down) allows for easier and faster assembly of the aircraft.
Attempts have been made to provide the desired adjustability in connecting bracketry. For example, support bracketry used on commercial aircraft that connects fuselage lining panels to the aircraft frame provides for adjustment by combining plates with slots oriented in different directions. More specifically, a pickup plate is solidly mounted to the aircraft frame by rivets or hi-lock fasteners, and a slotted bracket is mounted to the pickup plate such that the slots are oriented to allow for inboard/outboard adjustments. Rubber isolators, discussed below, are riveted to the slotted bracket. A slotted lining support bracket is mounted to the rubber dampeners such that the slots allow forward/aft adjustment. Finally, a slotted panel-pickup is mounted to the lining support bracket such that the slots allow for up/down adjustment.
This type of bracketry system utilizes many parts that are unique to particular installations, thereby minimizing the commonality of parts between installations and between aircraft. In addition, the bracketry is complex, heavy, and expensive to manufacture and install.
Another design concern regarding connecting bracketry, in conjunction with adjustability, is the minimization of noise created by vibration of aircraft components. When an aircraft is in flight, the airflow boundary layer on the aircraft's skin creates substantial vibration that is transmitted to the aircraft frame. To reduce vibration in components connected to the frame, and thereby minimize noise, vibration dampeners may be installed between the frame and adjoining components. As indicated above, it is further desirable to have an inexpensive common assembly with a minimum number of parts that may be installed easily to achieve the desired result.
In addition to achieving commonality, adjustability, and dampened vibration, a further design consideration in component-connecting bracketry is heat loss through the components; e.g., the frame and accompanying skin panels. In terms of commonality, it is highly desirable to use the same part to achieve two or more desired results. For example, one component that acts as a thermal isolator and as a vibration dampener in an easily adjustable bracket assembly.